A laptop personal computer (laptop PC) is sometimes equipped with a touch screen where a touch panel is combined with a display, as an input device, in addition to a keyboard and a mouse. The touch screen is a standard input device for a tablet terminal or a smartphone. The touch screen is operated with a finger by directly touching a screen itself or an object displayed on a screen and therefore is operable more intuitively and easily than moving a mouse cursor with a mouse, a Track Point®, or the like.
Furthermore, as another input device for a computer, there is a digitizer whose sensor panel is operated with an electronic pen. The digitizer is connected to a laptop PC through a wired or wireless interface, thereby enabling an operation by moving the mouse cursor displayed on the laptop PC with the electronic pen.
One electromagnetic induction type position detection device uses an input pen. In this position detection device, a plurality of sensor coils arranged on the coordinates sequentially repeats the transmission and reception of an electromagnetic wave to and from the input pen in which a resonance circuit is embedded. The sensor coil receives an electromagnetic wave oscillated by resonance through electromagnetic wave energy which the resonance circuit of the input pen received from the sensor coil and detects the position of the input pen and the pen pressure of the input pen from the intensity or phase thereof.